Congestive heart failure is a major problem in cardiology everywhere. The role of peripheral circulation in the development and manifestations of congestive heart failure needs further investigation in man. To study the peripheral circulation in the presence of congestive heart failure, three main approaches will be employed. 1) The rheoplethysmographic method will provide simultaneous recordings of digital inflow and outflow of blood in patients with CHF with and without the effects of drugs, vasoactive agents and other therapeutic measures. 2) Isolated forearm venous segments of patients with CHF will be studied to learn the venous responses to CHF and the above agents. 3) Digital biopsies will be examined histologically and electron microscopically to determine histologic and ultrastructural alterations of digital vessels in association with CHF and vasoactive substances. Peripheral vascular diseases are also major problems, both in etiology and management. In order to learn more about the pathology of the diseased vessels and factors which can cause the disease and influence the response to treatment, studies of the peripheral vessels and circulation will be conducted using the same methods noted above for CHF. The effect of viruses on the heart and other organs will be studied in experimental animals and in man with viral infection. Attempts will be made to relate pathologic changes in these organs noted by light microscopy, electron microscopy and immunofluorescence to clinical states associated with disease of these organs in man. In addition, studies of electrocardiography, vectorcardiography, effects of climate on the cardiovascular system, cardiomyopathies, and other aspects of our research on the heart and heart disease presently underway will be conducted as time permits.